A inspection jig, to which inspection contact elements have been attached, supplies electric current or an electrical signal from an inspection device to a predetermined inspection position on an inspection target section of an object to be inspected via the inspection contact element, and detects the electrical signal from the inspection target section, thereby carrying out a detection test to detect the electrical characteristics of the inspection target section, and carrying out an operational test on the inspection target section.
The object to be inspected may be, for example, a variety of boards such as a printed circuit board, a flexible board, a ceramic multilayer printed circuit board, an electrode plate for a liquid crystal display or a plasma display, and a package board or film carrier for a semiconductor package, and semiconductor devices such as a semiconductor wafer, a semiconductor chip, and a chip size package (CSP).
In the present specification, the objects to be inspected are collectively called an “inspection target,” and the inspection target section formed on the inspection target is called an “inspection section.” Further, an inspection point is set for the inspection section in order to actually inspect electrical characteristics of the inspection section, and the contact element comes into contact with the inspection section under pressure, thereby conducting electricity with the inspection section.
When the inspection target is, for example, a board, and when it is a semiconductor circuit such as an integrated circuit (IC) or an electric/electronic part such as a resistor or a capacitor that is mounted on the board, a wiring or an electrode formed on the board becomes the inspection target section. In this case, to guarantee an electrical signal to be able to be accurately transmitted to the wiring of the inspection target section, electrical characteristics such as the resistance or the leak electric current between inspection points formed on a circuit board having the wiring of a printed circuit board, a liquid crystal panel, or a plasma display panel on which the electric/electronic part has not yet been mounted are measured. On the basis of the result of the measurement, it is determined whether or not the wiring is poor.
When the inspection target is large scale integration (LSI), an electronic circuit formed on the LSI becomes the inspection section, and surface pads of the electronic circuit become respective inspection points. In this case, to guarantee that the electronic circuit formed on the LSI has the desired electrical characteristics, the electrical characteristics between the inspection points are measured, and it is determined whether or not the electronic circuit is poor.
Conventionally, a plurality of wirings are formed on the circuit board that is one embodiment of the inspection target. These wirings are formed to supply power or send an electrical signal such that the electric/electronic part mounted on the circuit board can carry out its desired function. For this reason, poor wiring is known to be associated with poor operation of the circuit board.
To solve these problems, many inventions for the inspection device have been proposed so that the inspection device can determine the poor or good quality of a target section, such as the wiring formed on the inspection target, such as a circuit board.
This inspection device carries out the inspection using, for example, an inspection jig, which includes a plurality of inspection points preset on a wiring and a plurality of contact elements (probes) connected to the respective inspection points, in order to determine the poor or good quality of the wiring formed on the board acting as the inspection target.
This inspection jig is configured so that one end of the contact element comes into pressure-contact with the inspection point on the wiring (inspection section) and so that the other end of the contact element comes into pressure-contact with an electrode part electrically connected with the board inspection device. Thus, electric current or voltage for measuring electrical characteristics of the wiring is supplied from the board inspection device via the inspection jig, and an electrical signal detected from the wiring is transmitted to the board inspection device.
With the recent advancement of technologies, the wiring on the board is also adapted to be formed in a more minute and complex way along with miniaturization of semiconductor devices or miniaturization of boards. As the miniaturization and complexity increase of the wiring of the board are underway, the contact elements of the inspection jig are also requested to be made thinner or smaller, narrower in pitch between the contact elements, to have more pins, or to be simpler.
Here, for example, a micro-contact probe disclosed in Patent Document 1 suggests that a pair of plungers urged in a reverse direction by a coil spring are electrically connected via a densely wound spiral part, thereby decreasing inductance and resistance.
In Patent Document 1, as a second embodiment, a micro-contact probe formed by inserting a pair of plungers into the coil spring having a greater diameter than each of the pair of plungers is disclosed. By forming this contact probe, the plunger that comes into contact with an inspection point can come into contact under stronger pressure, and the plunger that comes into contact with a wiring plate can come into contact under weaker pressure. Further, due to a dual structure, the plungers can be attached in a small space.
However, since the micro-contact probe shown in Patent Document 1 is formed with the coil spring by winding, it is difficult to form a coil having about four times as small a diameter as the coil spring has, and it is very difficult to form a winding coil spring having an outer diameter of 100 μm or less and to assembly it as an inspection contact element. Even if so, it is excessively expensive to employ an inspection jig using 2000 to 4000 inspection contact elements due to a problem of manufacturing cost. As such, the micro-contact probe has a problem that it is not practical. Further, it is necessary to assembly a plurality of parts with high precision, which requires a lot of time.
Furthermore, if the contact element whose diameter is reduced to cope with a tendency to narrow a pitch is manufactured, sufficient contact pressure is not obtained. Thus, an oxide layer formed on a surface of the inspection point cannot be sufficiently destroyed, and contact resistance is not made stable when the inspection is carried out.    Patent Document 1: International Patent Application Publication No. WO2001/09683